[idspispopd]

Quality of membership(i.e actual use) is more important than raw membership numbers. Those who seek out LinkedIn/Facebook/others are likely to be more interested in using the service than someone who joined G+ because their default search engine asked them to enter their google services password to instantly become a member.

A comparable example is Apple's Ping. Apple doesn't tout Ping as a success because it has millions of members (who were similarly presented with a trivial sign up method in iTunes 10 - Ping registered over 1M users in the first 48 hours.) Ping, however, is rarely used by the bulk of it's members, as such it's being discontinued. Most people signed up just to see what it was like, they didn't stick around. Facebook/LinkedIn don't have this problem so much, most people already know what the services are for, so they don't need to create a profile just to see what it's like.

G+ is growing, but it's an overstatement to say that it has the same level of user engagement as facebook/LinkedIn/others.

While many continue with the faulty logic that G+ is a superior experience/platform so it should become the dominant service, need to revisit the learnings of Betamax: technical superiority does not equate to automatic or guaranteed success.